1. Technical Field
The present invention relates to a push-type switch device such as a push switch, and more particularly, to a push-type switch device configured to output an on signal when a driving protrusion pushed by a user reverses a reversing spring of a switch element.
2. Related Art
In a push-type switch device, a dome-shaped reversing spring formed by a conductive metal plate is used as a movable contact point of a switch element, and the reversing spring faces a fixed contact point of the switch element so as to move close to or away from the fixed contact point. In addition, a driving protrusion as an actuator is disposed above the center portion of the reversing spring, and the driving protrusion is adapted to push down the center portion of the reversing spring during a push operation of the switch device. When the center portion of the reversing spring is pushed down by a predetermined amount, the reversing spring is elastically deformed in a buckling manner to be reversed while generating a click feeling, and contacts with the fixed contact point provided below the reversing spring. That is, when the switch device is pushed, the reversing spring pushed by the driving protrusion to be reversed contacts with the fixed contact point provided below the reversing spring, so that an on signal is output and a user's finger feels a switching operation from an off state to an on state by means of a click feeling generated upon reversing the reversing spring.
This kind of push-type switch device is used while being mounted on an interconnection substrate. However, since the switch element having the reversing spring and a member for guiding the up-down movement (reciprocation movement) of the driving protrusion are individually attached to the interconnection substrate, a relative position between the reversing spring and the driving protrusion may easily change. For this reason, upon pushing the switch device, the driving protrusion may easily push a portion deviated from the center portion of the reversing spring. In this case, a problem arises in that the reversing spring cannot generate a clear click feeling or the reversing spring cannot be operated in a normal state due to a plastic deformation thereof.
For this reason, a switch device which allows a driving protrusion to reliably push a center portion of a reversing spring during a push operation of the switch device was proposed in US Patent Publication No. 2003-0042121 (corresponding to JP-A-2003-77364), where the switch device has a configuration in which a lower end portion of a driving protrusion is adhered to a center portion of a reversing spring in advance to be fixed thereto so as to simultaneously move up and down all the time without the worry of the positional deviation therebetween.
However, in the above-described known example, since the push-type switch device has a configuration in which the driving protrusion is adhered to the reversing spring to be fixed thereto, a complicated assembling operation is required to adhere the driving protrusion to the reversing spring to be fixed thereto while performing an accurate positioning operation therebetween. Further, a problem arises in that an adhesive has a negative impact on a reversing characteristic of the reversing spring and high reliability of the switch device cannot be maintained if a crack is generated in the adhesive caused by the repeated push operation. In addition, when the driving protrusion is adhered to the reversing spring to be fixed thereto, the driving protrusion cannot be rotated. Accordingly, in order to obtain a multi-functional switch device which can be both pushed and rotated, a plurality of manipulation members needs to be disposed so as not to interfere with each other. In this case, a problem arises in that the structure of the switch device becomes complicated and the cost thereof inevitably increases.